Manufacture of spun yarn



July 2, 1957 TAKEQ TAKAGI ET AL 2,797,444

MANUFACTURE OF SPUN YARN Filed July 7, 1953 IN V EN TORS.

771x50 774K/7Ql BY K/JZ U0 uni/Z WM V ATTORNEY MANUFACTURE OF SPUN YARN Takeo Takagi, Tokyo, and Kazuo Ueda, Tokushima Prefecture, Japan, assignors to Toho Rayon Co., Ltd., Tokyo, Japan, a corporation of Japan Application luly 7, 1953, Serial No. 366,530 Claims priority, application Japan November 14, 1951 I 5 Claims. (Cl. 19.4 1)

The present invention relates to improvements in the manufacture of spun-yarn from a bundle of continuous filaments in accordance with the double draft zone system.

More specifically the invention relates to an improved apparatus and method of breaking the filaments to form staple of a substantially uniform length in a continuous yarn spinning operation of the type referred to.

In accordance with the double draft zone system of producing spun yarn from continuous filaments, the bundle of filaments or tow is preferably spread out into a uniformly thin sheet, is drawn through a group of back breaking rollers, between a pair of front breaking rollers driven at sufficiently higher peripheral rate to break the filaments forming the tow, and thence through a pair of front rollers which are driven at a still faster rate adjusted to effect the draft necessary to obtain the required yarn count. Finally, the tow is collected and wound with some twist into the form of a spun yarn on a ring spinning frame, or on a pot spinning machine.

It is a principal object of the present invention to provide a novel and improved apparatus and method of breaking the filaments of the tow in accordance with the double draft system which will have the effect of producing an improved sliver or thread formed of staple which is of substantially uniform length and which will contain not more than a very low percentage of short lengths.

It is a further object of the invention to produce from a bundle of filaments an improved spun yarn which will have in high degree the characteristic softness and fullness of staple yarn and will at the same time have greater strength and durability than is normally associated with such yarn.

The invention will be more particularly described in connection with the accompanying drawing, in which Fig. 1 is a somewhat diagrammatic view showing the arrangement of the breaking and drafting rollers and leather supporting aprons of a machine of a type well known in the art for breaking and drafting the tow to form a yarn sliver of spun yarn, and which further embodies in a preferred form the several features of the invention.

The apparatus illustrated in Fig. 1 of the drawing consists of a spool from which the tow, generally indicated at 12 is drawn. The tow passes through a spreader device which may be of any well known description and is here shown as two relatively stationary rods or rollers 14, 16, and an intervening roller 18, which is continuously reciprocated bodily between the solid line and dotted line positions shown in order to spread out the tow into a relatively thin flat sheet. The tow is then drawn through an aggregation of three back breaking rollers 20, 22 and 24, being guided on a leather apron 26 which passes also over a tightening roller 27. Further elements of the breaking and drafting apparatus well known in the art include a pair of front breaking rollers 28, 30, and a leather apron 32 which passes with the tow between the tWo rollers over a guide rod 34, around a guide tion.

2,797,444 s ete ed M 9 2 bar 36 and thence around a driving roller 38. The tow is then drawn between two drafting rollers 40, 42 in order to effect the drafting of the tow to produce the desired yarn count. are provided two' clearer rollers 44, 46. In the preferred form of the invention the yarn is then delivered through a guide 48 to a winding device which may be a spinning spindle 50 as shown or the rotating pot of a centrifugal pot spinning device for winding and for imparting a desired amount of twist to the sliver.

It will be noted that the distance between the nip or point of gripping contact of the back breaking rollers with the tow 12 and the nip or point of gripping contact of the two front breaking rollers 28, 30 with the tow is approximately 5%". The distance between the nip of the front breaking rollers 28, 30 and the nip of the front rollers 40, 42 with the tow 12 is approximately 6%".

In accordance with the invention a friction roller 54 is supported in engagement with a portion of the tow, passing from the rear breaking rollers 22, 24 to the front breaking rollers 28, 30 in such a manner as to form a bend in the tow. The drive from one set of rollers to the next is generally indicated by dot-and-dash circles indicating a series of driving gears. Thus, roller 30 is driven from roller 24 and is in turn geared to drive friction roller 54 and front roller 42. The roller 54 is positively driven at a substantially faster rate than the front breaking rollers 28, 30. The relative rate of drive' for the rear and front breaking rollers is adjusted in ac-- cordance with the requirements of the particular filaments being drawn through the apparatus. For the breaking and drafting of a tow composed of viscose filaments it may be assumed that the surface speeds of the back breaking rollers 22, 24, the front breaking rollers 28, 30, and

the front rollers 40, 42 are in the ratio of 1:(between 2.5 and 4):(between 30 and 60). It will be understood that the ratio chosen is subject to substantial varia- The drive of the front breaking rollers 28, 30 at a rate 30 times the surface driving rate of the rear breaking rollers 22, 24 is sufficient to break the filaments of the tow. The draft'ratio of the front rollers 40, 42 noted to be in the order of .10 to 15 times the surface driving rate of the front breaking rollers-28, 30, is readily varied in accordance, with the requirements of yarn count and fineness of yarn desired.

Further in accordancewith the invention the interposed friction roller 54 is driven at a substantially faster rate than the tow 12 which is being continuously drawn out during its travel from the back breaking rollers to the front breaking rollers 28, 30. The linear rate of drive of friction roller 54 may be in the order of from 65-130 times the linear rate of drive of the rear breaking rollers 22, 24. An off-winder 56 is provided immediately adjacent the friction roller 54 to clear the friction roller from fibers. The off-winder 56 has been found to be of substantial value to eliminate the winding of. broken fibers or staple onto the friction roller, and has contributed to the'production of a yarn of greatly improved quality with less nap. I

The friction roller 54 as shown in the preferred form t in Fig. 1 is provided with a saw-toothed friction surface.

It will be understood, however, that friction surfaces of other types may be employed, as for example, a plain surface, or one that is leather-coated, rouletted, fluted,

screwed or file-finished, as may be desired.

In order to carry out most effectively the objects of the invention the frictionroller 54 is located out of align- Adjacent the rollers 40, 42 there the friction roller 54. With the illustrated construction the breaking points of the individual filaments are concentrated in the vicinity of 13 to 14 millimeters from the friction roller. The breaking of the individual filaments, however, is sufiiciently at random within this area to prevent a complete separation or breaking of the tow, so that the bundle form of the sliver is maintained. A continuous sliver having a substantially uniform staple length is formed which compares favorably with respect to uniformity of staple length, strength, fullness and the like with spun yarns formed from cut staple, and at a small fraction of the cost. The subsequent drafting operation which takes place during passage of the tow from the front breaking rollers 28, 30 to the front rollers 46, 42, causes the tow to be reduced to the required yarn count. The subsequent spinning operation results in the manufacture of an excellent spun yarn of great strength and having a high degree of uniformity.

A comparative table is here produced to illustrate advantageous yarn qualities obtained by the herein disclosed method and apparatus. A comparison is made specifically between runs of material through the breaking and drafting apparatus illustrated including the friction roller 54, above described and illustrated, and similar runs through the same apparatus except that the friction roller 54 has been omitted.

With fric- Without tion friction roller roller Water content .percent. 14. 13.6 Dry grain .gr. 22. 1 22.0 Corrected count 40. 8 40. 9 Leo strength (dry). .lbs 82. 4 61. 6 Lea strength (wet)- .lbs. 42. 0 37.3 Lea elongation (dry). percent.. 5. 56 5. 45 Lea elongation (wet) do 6. 52 5. 99 Twist (obsd.) t. p. L. 19.10 18.35 Twist (0210.) t. p. i 19. 40 19. 40 Twist const 3.0 2. 0 Single yam, tensile strength gr- 267. 4 222. Single yarn, elongation percent... 5. 71 5.12 Staple length:

max ..mm 155 166 mi.n .mm. 48 18 aver .mm 140 74 From the foregoing comparison it will be noted that spun yarn produced in accordance with the so-called double draft system is very substantially improved by the inclusion of a friction element in the breaking zone between the back breaking rollers 22, 24 and the front breaking rollers 28, which engages against and has a surface rate of travel with and at approximately 65 to 130 times the surface rate of travel of the rear breaking rollers 22, 24. The elfect of the frictional engagement of the friction roller 54 with the individual filaments of the tow is to concentrate the breaking of the tow at the point of engagement with the friction roller, substantially no breakage taking place any appreciable distance either side thereof. As shown in the above table the filaments are broken into substantially uniform lengths averaging 140 millimeters, with maximum and minimum limits of 155 millimeters and 48 millimeters respectively. This compares with an average staple length of 74 millimeters with maximum and minimum limits of 166 and 18 millimeters respectively for spun yarn produced with the same breaking anddrafting apparatus, but without the addition of the friction roller 54. With the increase in staple length thus achieved a stronger, fuller, and more desirable spun yarn is created, having substantially greater strength characteristics, both wet and dry, and a materially greater tensile strength of the single yarn.

The invention having been described what is claimed is:

1. Apparatus for drafting'and breaking a tow of continuous filaments to form spun yarn whichcomprises' back breaking rollers and front breaking rollers spaced from" the back breaking. rollers'and arranged to be'driven'at a filament breaking ratio to the back breaking rollers, and a friction roller engaging the tow between said back and front breaking rollers, said friction roller being continuously moved in the direction of movement of the tow at a rate substantially in excess of the peripheral surface rate of said front breaking rollers and between 65 and 130 times the peripheral rate of the back breaking rollers, whereby the breaking point of the individual filaments extending between the back and front breaking rollers is concentrated about the area of contact of said friction roller with said tow.

2. Apparatus for breaking and drafting a tow of continuous filaments to form spun yarn which comprises back breaking rollers engaging the tow therebetween, front breaking rollers spaced from and arranged to be driven in a filament breaking draft ratio to the back breaking rollers, and a friction roller interposed between the back and front breaking rollers engaging and forming a bend in said tow and adapted to be driven at between 65 and 130 times the peripheral rate of the back breaking rollers whereby the breaking point of the individual filaments extending between the back and front breaking rollers is concentrated about the area of contact of said friction roller with said tow, and an off-winder for separating the staple fiber from the friction roller.

3. Apparatus for breaking and drafting a tow of continuous filaments in accordance with the double zone direct spinning system which comprises rear breaking rollers and front breaking rollers spaced therefrom forming a breaking zone, and arranged to be driven at a filament breaking ratio with respect to the back breaking rollers, and an intervening friction roller engaging and forming a bend in said tow and adapted to be driven at between 65 and 130 times the peripheral rate of the back breaking rollers whereby the breaking point of the individual filaments extending between the back and front breaking rollers is concentrated about the area of contact of said friction roller with said tow.

4. Apparatus for breaking and drafting a tow of continuous filaments in accordance with the double zone direct spinning system into a sliver of spun yarn, which comprises rear breaking rollers, front breaking rollers spaced from the rear breaking rollers to form a breaking zone, front rollers spaced from the front breaking rollers to provide a draft zone, and a friction roller spaced from the back breaking rollers in the breaking zone to engage withand form a bend in said tow, and driving means for driving the rear breaking rollers, the front breaking rollers and the front rollers at peripheral rates in the ratio of 1 :(between 2.5 and 4):(between 30 and and for driving the friction roller at a peripheral rate with relation to the back breaking rollers in the ratio of 1:(between and whereby the breaking point of the individual filaments extending between the front and back breaking rollers is concentrated about the area of contact of said friction roller with said tow, and a long staple yarn of substantially uniform length is produced.

5. Apparatus for breaking and drafting a tow of continuous filaments in accordance with the double zone direct spinning system into a sliver of spun yarn, which comprises means for spreading the tow, back breaking rollers engaging the tow spread therebetwecn, front breaking rollers spaced from the back breaking rollers providing a filament breaking zone, front rollers spaced from the front breaking rollers providing a draft zone, a friction roller spaced from the back breaking rollers to engage with and form a bend in said tow, and driving means for driving the front breaking rollers in a filament breaking ratio to the back breaking rollers, for driving the front rollers in a drafting ratio to the front breaking rollers, and for driving the friction roller at a rate substantially greater than the peripheral rate of the front breakingrollers whereby the breaking point of the indi- F vidual filaments in the filament breaking zone is concen- 6 frated about the area of contact of said friction roller 2,077,320 Hale et a1. Apr. 13, 1937 with said tow. 2,419,320 Lohrke Apr. 22, 1947 2,635,295 De Lacotte et a1 Apr. 21, 1953 References Cited in the file of this patent 2,640,228 Burnham June 2, 1953 UNITED STATES PATENTS 5 2,688,160 Cooke et a1. Sept. 7, 1954 1,959,142 Taylor May 15, 1934 

